Mercenary : a person who takes part in an armed conflict, who is not a national or a party to the conflict, and is "motivated to take part in the hostilities essentially by the desire for private gain and, in fact, is promised, by or on behalf of a party to the conflict, material compensation substantially in excess of that promised or paid to combatants of similar ranks and functions in the armed forces of that Party" (Additional Protocol I to the Geneva Convention of August 1949)